Kitson made 45 minutes of non-stop pressure count to keep the U's ahead of the Cod Army at the top end of League Two.
They had blown a fantastic chance to cancel out Steven Schumacher's opener when Kitson tumbled in the box and Fleetwood man Danny Rose's stop kick was saved.
But Oxford's persistence paid off at the death when Kitson turned a cross home to earn a point for the Us.
"I'm delighted with the reaction to going a goal behind, to a fantastic goal at that," Wilder said.
"Last year we came here and deserved to go away with nothing. People who watched the game can say we were the dominant team, particularly in the second half.
"David Kitson has been outstanding for us. Second half he played further up pitch and the effort and the energy levels from the players was phenomenal as we were going for it.
"After we've scored the equaliser we've gone on for a winner.
"There are defining moments in any season and hopefully this is one of them."